1. Field of the Invention
The present invention relates to the technical field of display panels and, more particularly, to a display panel driving and scanning method and system.
2. Description of Related Art
FIG. 1 is a schematic diagram of a typical display panel driving method. As shown in FIG. 1, the driving scheme sequentially activates scanning signals in one frame period. For example, it starts to scan sequentially from the first line L1 to the last line Ln. For each line to be activated, the data to be displayed is written in the display panel through the data channels (S1-Sm). At this moment, the display panel can follow the scanning sequence to sequentially display the input data, so that the full frame is displayed immediately when the scanning completely ends.
The panel display driving method in the prior art may encounter one special problem in actual application. Namely, the displayed data between the tandem scanning lines has one frame time difference, which can easily cause a flicker on visual effect and further produce a smearing effect.
In comparison with a liquid crystal display (LCD) panel and a conventional cathode ray tube (CRT) screen, the smearing effect on a frame of the LCD panel is one of most disadvantages for the LCD. The currently popular liquid crystal response time can reach above 8 ms, but the liquid crystals somewhat have a certain degree of smearing.
The signal responses in many prior arts are gradually shortened to 5 ms, 4 ms, 2 ms, or even 1 ms. However, when the LCD panel displays a high-speed motion frame, the smearing phenomenon still appears. Thus, the smearing phenomenon on the liquid crystals is a serious problem to be overcome.
For a further description, there are two factors that may cause the smearing phenomenon. The first factor is that, in view of the liquid crystal operation principle, each pixel point on an LCD frame uses the twisted nematic liquid crystal molecules to control the intensity of an irradiated light. The irradiated light is outputted by a backlight source that is in a lighting state all the time. The LCD panel presents a so-called “hold-type” display for the pixel signals since the viscous liquid crystal molecules are difficult to completely block a pierced light, the backlight source is open all the time, and so on. That is, the continuity of each interval between the signals is stronger, which can allow the human eyes to sensitively capture a “memorized” previous frame in a rapidly switching frame process due to the visual staying phenomenon to thus overlap or mix with a newly presented frame, or more seriously produce the smearing phenomenon.
The second factor is that the visual staying phenomenon of human eyes also causes the smearing phenomenon. Since the vision of human eyes remains an object's image for a while after the object disappears, the visual staying phenomenon can cause the human eyes to have the smearing of a frame even though the LCD response time is very fast.
The current response time is reduced to 1 ms at most, which is done by precisely controlling the driving voltage of a display so as to shorten the response time between the gray levels. However, the smearing phenomenon or afterimage still exists even the response time is shortened to the limit.
Accordingly, for the liquid crystal smearing phenomenon, a typical black frame insertion technology is used to eliminate the phenomenon. A black frame is periodically inserted between two frames, so as to avoid the blurring effect on the edges that is caused by the special imaging mechanism of human eyes in frame switching, and further eliminate the liquid crystal smearing phenomenon. Since the human eyes have the visual staying phenomenon, the black frame inserted between the two frames by the black frame insertion technology can cancel the visual staying time of the human eyes and eliminate the liquid crystal smearing phenomenon.
U.S. Pat. No. 6,693,618 granted to Son, et al. for a “Liquid crystal display device and driving method for the same” has disclosed a black frame insertion. Namely, it divides each frame into two subframes for displaying the image data and the black frames to thereby reduce the image display time and improve the afterimage of an LCD. However, such a black frame insertion has to completely display the current frame and the black frame in an original frame display time, resulted in increasing the frequency of the driving clock CLK. Thus, the power consumption of the TFT LCD 10 is correspondingly increased to disadvantage the utilities of the portable electronic devices. In addition, the typical black frame insertion is a frame-based process, and an uneven frame may occur when the original frame and the black frame do not have a ratio of 1:1. Besides, the backlight source is turned on all the time when the black frame insertion is operated, resulted in consuming much power.
U.S. Pat. No. 8,013,829 granted to Chen, et al. for a “Liquid crystal display having black insertion controller selecting black insertion control signals according to data stored therein and driving method thereof” has disclosed a black insertion controller. In this case, one frame period T0 is divided into a first subframe period T1 and a second subframe period T2. FIG. 2 is a schematic diagram of a typical LCD panel scanning timing. As shown in FIG. 2, the liquid crystals are driven to display a normal image unit or a black image unit in the first subframe period T1 according to an address, and the liquid crystals are driven to convert the normal image unit into a black image unit or convert the black image unit into a normal image unit in the second subframe period T2 to thereby improve the smearing phenomenon. However, although the liquid crystal smearing phenomenon can be alleviated, it cannot be completely eliminated. In addition, in the frame period T0, the backlight source needs to be turned on all the time, which consumes much power.
Therefore, it is desirable to provide an improved display panel driving and scanning method and system to mitigate and/or obviate the aforementioned problems.